Statistics

Question 1

What are the four different scales of measurement?

Answer 1

• NOIR
• Nominal
• Ordinal
• Interval
• Ratio

Question 2

Describe the Nominal Scale of Measurement

Answer 2

• Numerals represent category labels only

- Sex, Nationality, Blood Type, etc

Question 3

Describe the Ordinal Scale of Measurement

Answer 3

• Numbers indicate rank order
• Intervals may not be equally spaced
• Manual Muscle Test, NPRS, Etc

Question 4

Describe the Interval Scale of Measurement

Answer 4

• Equal Intervals Between Numbers
• Not related to true zero, not representing absolute quantity
• Calendar Years, IQ level

Question 5

Describe the Ratio Scale of Measurement

Answer 5

• Numbers represent units with equal intervals
• Measured from True Zero
• Distance, Age, Weight, etc

Question 6

What is Predictive Validity?

Answer 6

• Attempts to establish that a test with be a valid predictor of some future criterion score
• SAT test used to determine future academic success at college

Question 7

What is Construct Validity?

Answer 7

• The ability of a test an instrument to measure an abstract concept or construct
• Never fully realize due to the difficulty to define constructs (because constructs are not “real”)

Question 8

What is a Positive Predictive Value?

Answer 8

• The likelihood that a person who tests positive actually has the disease
• Number of patients with the disease divided by Number of positive tests

Question 9

What is a Negative Predictive Value?

Answer 9

• Probability that a person who tests negative does not have the disease
• Number of patients without disease divided by Number of Negative Tests

Question 10

What is Prevalence?

Answer 10

• Number of cases of a condition existing in a given population at any one time

Question 11

What is Incidence?

Answer 11

• Number of new cases of a condition over a certain period of time

Question 12

What is effect size?

Answer 12

• Standardized measure of change ranging from 0-1
• Below .4 small
• .5 Moderate
• .8 Large

Question 13

What is a research Hypothesis?

Answer 13

• The researchers true expectation of the results

Question 14

What is the Statistical/ Null Hypothesis?

Answer 14

• Expectation that there will be no difference between independent and dependent variables

Question 15

What is the difference between a Single Blind and Double Blind Study?

Answer 15

• Single Blind, only investigator or subject is blinded

- Double Blind, Investigators and subjects are blinded

Question 16

What is Type 1 Error?

Answer 16

• The Risk of saying a difference exists when one does not
• Backing a Loser
• Expressed by Alpha value, Typically at .05

Question 17

What is Type 2 Error?

Answer 17

• Risk of stating there is no difference when one does exist
• Rejecting a Winner
• Expressed by Beta, Typically between .05 and .20

Question 18

What are the Determinants of Statistical Power?

Answer 18

• SAVE
• Sample Size
• Alpha Value
• Variance
• Effect Size

Question 19

What is Face Validity?

Answer 19

• Instrument appears to test what it is supposed to test

Question 20

What is Content Validity?

Answer 20

• Items that make up an instrument adequately test the universe of content that defines the variable being measured
• Used Most often in questionnaires

Question 21

What is Concurrent Validity?

Answer 21

• Establishes validity when two measures are taken at relatively the same time
• Used when target is considered more efficient than the gold standard